Bad sheds are a husbandry issue that don't get fixed immediately. Your snake was probably dehydrated when his skin currently being shed was forming, so it's been too dry all along. His next shed will likely be better but not perfect. Also adult retics rarely have perfect sheds as they're rather enthusiastic about removing it, so it will be shredded into pieces anyway.
You can help by keeping him well hydrated (high humidity, feeding f/t feeders wet, etc) but it will take a while.
Bathwater temps over 90*F are too high, you want them 85-90*F. In addition to soaking him use a small towel or large washcloth to gently rub the shed off. These guys are smart and eventually they do figure out that you're helping them.