You must make sure the litterbox is kept extra clean. Scoop it every time a kittie uses it. If the cat still pees on your bed, it may be jealousy over another cat or a human, and he's marking you as "his". This will probably stop when you have him neutered. Check with a vet to see how old they have to be to get fixed.
I do clean the kitty box every day, and I never thought about him marking me as his. My other cat Christopher is the only one allowed to sleep with me. That was the deal my husband and I made when we took on Rayne. It is strange that he only pees on MY side of the bed, never my husbands. He may be jealous that he does not get to sleep with me. I found out that he has to be 4-6 months old before he can get fixed, he is about 8 weeks now. Thanks