How do I pay for prerequisite classes for Masters program? (I have an irrelevant bachelor’s)

I have a bachelor's in nursing science but my goal is to get a master's degree in molecular and cellular biology. From the bit of research I've done I don't think I have the necessary prerequisite classes and skills. I know I don't need all of them but I still need to take some higher level math, chemistry, physics, and computer science.

I am trying to figure out the best way to get those classes done (and paid for lol). Sounds like I need to be enrolled in a degree program but since I don't have enough experience to apply for the Masters program I want I'm not sure if it would work to enroll in some biology or chemistry program through my local University for a bachelor's? Because I don't think the military will pay for another bachelor even though that's not my goal…

I could ultimately pay out of pocket but I would like to make you some tuition assistance or other available military assistance if possible. Any thoughts?

Tldr how do I get prerequisites paid for a master's degree when I already have a bachelor's?