Here's a simple solution for pax who click their fingers at you:
Say "are you ok?" (or similar), then NICELY explain that clicking their fingers at you is not very nice and to please not do it again.
I've said this a fair few times and usually, the pax in question apologises profusely and explains they didn't realise it was rude in our culture.
The same goes for tugging/poking of body parts/items of crew clothing. I simply say "please don't touch me/poke me/tug at my clothes, as I don't like it". That usually makes them understand that it's not acceptable.
Gg