Hi there! Welcome to PT! Do you have any pictures?

For advice, I suggest crate-training. Is that what you're doing already? Keep him in a dog crate/kennel while you are away or when you are too busy to pay attention to him. It will be his "den," or "safety-zone," and shouldn't pee or poo in it if it is small enough. Hang a bell by your that leads to where he should go pee. And whenever you take him out, ring the bell first. Soon he will learn that if he wants to go out, he should ring the bell to let you know.

Good luck!