I think as long as you don't react when he does things like that, as then he's only receiving 'negative attention' and kids will take any attention. Sticker chart for good behaviour, focusing on positive behaviours is the best way and like you are doing, make him help you clean it up too (without too much fuss from you) just go "ok so now we need to clean this up, remember, we do wee's on the toilet only as you're such a big boy now" etc....