How is the AND/OR operator represented as in Regular Expressions?

I’m going to assume you want to build a the regex dynamically to contain other words than part1 and part2, and that you want order not to matter. If so you can use something like this:

((^|, )(part1|part2|part3))+$

Positive matches:

part1
part2, part1
part1, part2, part3

Negative matches:

part1,           //with and without trailing spaces.
part3, part2, 
otherpart1