First of all I think your son is still very young and many behaviours are due t the lack of their ability to express themselves verbally.
You tell your son hits and seems to know what he’s doing as when you say no he’ll be doing it anyway
I would do the opposite of what many suggest.
* take away the DON’T and turn them into DO
* so instead of telling him no hitting, praise him when he has beautiful gentle hands and make sure to give him a big fat hug
* ignore the negative behaviour and praise the postive behaviour;
* when he hits you in the face I would turn around and walk away, no eye contact ! then when he seeks attention in a positive way, switch on with warmth (in a way this is the same as time out; you take attention away and attention seems to be what he seeks)
* any attention on a certain behaviour -whether it is positive or negative- is reinforcing
* make sure you give him enough postive attention in general
* make sure not to yell; yelling at kids can be just as harmful as hitting them; effects from harsh physical and verbal discipline are found to be frighteningly similar. A child who is yelled at is more likely to exhibit problem behavior, thereby eliciting more yelling. It’s a sad cycle.
* teach your son alternatives,
* offer plenty of choices
* use redirection before the behaviour occurs (take the trigger away).
* Look at the behaviour in a way of trigger-behaviour-consequence and look to what maintains the behaviour and break that cycle.

Just keep being firm and consistent. At his age pushing boundaries is the norm. He will eventually learn

Time outs if he does something wtong rouse at him if he does it again set him down alone with no toys and nothing to play with and leave him there for a few minutes no doubt he will cry and try to follow you but ignore the tears and put him back

You need to take him away from the situation he is in, he needs to learn that behaviour hurts and isn’t nice, so by taking him away from the fun, he will learn quickly it’s not on.

Time out whenever he does this. 2 minutes away from everyone. After the two minutes he has to say he is sorry or he goes back for another 2 minutes. You have to be consistent though. The first day doing this will be the hardest, but you have to stick to it once you start.

Be careful you’re not rewarding his behaviours by giving him more attention after he hits you. Sometimes kids do it for the attention they get even if it is your negative attention. Distraction and prevention are the best strategies but I realise these are not always possible.

explain that what he is doing is wrong and isolate and ignore

i would try taking something away that he likes and see how that goes

Taking him away from the situation, exclude him to show him what he has done is not acceptable..he will click very quickly that hitting people gets him removed from the fun environment

I like prevention and distraction rather than harsh words or even punishment and anger, it’s not always easy but children at your sons age can be distracted and if you can recognise the signs of when he starts to get angry or violent then you might be able to get in first and distract him?

There are a lot of tantrums at this age! So, let me get this straight: he’s 3/4 of a metre tall & slapping you in the face??? Is it while you’re carrying him? I’d hold his free hand while carrying him, like in a dance pose – which I do with my almost 15 m/o daughter so she doesn’t wobble me off balance. Distraction is the main thing. Clear away things to throw & give him things you don’t mind him throwing – like a balloon, inflatable books, soft toys. Good Luck.

maybe you need to also change the tone of your voice, so he knows your angry at him

He is not too young to be told no, and to receive discipline. While he probably wouldn’t be willing to sit on a “naughty mat” for a couple of minutes, putting him into a cot or playpen (with no toys) for a couple of minutes will show him that there are consequences to doing something when Mummy says no.

I would put him in time out once he’s done it don’t talk to him just pick him up sit him in time out set a clock for say 5 minutes so a alarm goes off and each time he does it just keep going with the time out. I know its hard but he will keep doing it if he gets a reaction from you hence why i say just pick him up without talking to him
Good luck

I used a port a cot as a time out corner, only for a minute, but those behavious dimished within 2 weeks of doing this with my son. Smacking back only reinforces the “well if you do it, why cant i?”