How to wipe certain clients during BM change?

I have some clients who are not potty trained. They move around a lot and don’t lay down for the BM wipe. How would you go about cleaning these types of clients? I don’t want to leave them dirty and I’m also afraid of being too restrictive/invasive with them. There’s also not enough staff at my clinic to support me in this type of situation, so I have to handle it alone.