how can i access the player who touched the part? (FireClient() related problem)

Basically, I'm trying to get the player who touched the part, however, I've tried many different methods, and none of them seemed to work. Tried using IsA(), WaitForChild() functions, player.Parent and many others. So is there any possible way? (all of the scripts are placed and written in the correct order)

There is a GetPlayerFromCharacter function which returns the player object from the character object

game.Players:GetPlayerFromCharacter(CharacterThatTouched)