Something like a Comp Tac Infidel will work pretty well for your purposes. You can throw it IWB, snap the loops and carry it openly, concealed, or loosely concealed with that light covering garment. Get to work, pop the snaps and throw it in the glovebox. Again, it doesn't have to be this holster but something like it should work well for those purposes, especially now that we have open carry options.
http://www.comp-tac....?products_id=68
I agree with Jeff on paddle holsters. They're a great range holster option if your OWB belt-slide holster has a paddle model brother. I would not open carry with one. The attachment point of the holster body to the top of the paddle is a weak point in a struggle. A very weak point. If you have to go OWB, go with a belt slide. The snap-on models like Jeff was talking about are a good option for your situation with work but I would look at an IWB with the same capabilities, first.