We used prefolds and Bummis wraps mostly. We did have a few training pants, but never used them. All 3 of mine decided they wanted to use the potty & went to undies or naked and that was that. I'll throw on a trainer at naptime if they didn't use the potty first (2 year olds!!). I think the cloth helps, especially if you change them quickly, because they actually get to feel when they are wet and are used to getting the wet diaper off right away. With warmer weather coming, can you just put a teeshirt on your DS so he use the potty quickly and SEE what happens when he doesn't? Also, being around potty trained children can help, so if you have friends with toddlers/preschoolers, spend some time watching them go potty.
All of mine started showing an interest in the potty at about the same age that your DS is now. We got them potty chairs & suggested that they sit on them at diaper changes, maybe read a book if they were interested. Certainly put them on the potty if they asked at other times!. Beyond that, we did no "training". My oldest DD fought diaper changes violently starting at about 18 months, so I spent a lot of time saying, "When you are ready to go peepee in the potty, we can get underwear instead of diapers." One morning, she absolutely refused a diaper. I reminded her to use the potty, and that was that. She was 26 months. I couldn't figure out what all the fuss was about, LOL. Her twin brother then wanted to wear undies, and we spent about a week changing his clothes about 6 times a day because he just wasn't aware when he was about to pee. It took him about 5 more months before he decided to try again. We put him in undies and he had about a week of mostly successes with a few accidents. Then was fine. DD2 was the youngest to show an interest. It helps to have big kids around! She was in/out of diapers for several months, sometimes wanting a diaper, then wanting undies for several days or even a week or two, before deciding she only wanted undies. She was about 21 months when she stopped wearing diapers entirely during the day. We had more accidents during the transition with her, I think because she was so young, and we went through a spell right when she turned 2 when she refused to tell us until the pee was actually coming out (and was being very "2" so wouldn't use the potty unless it was her idea). Damp undies are still easier than washing a pail full of diapers, though.