What is your case model, because it MAY have a build in fan hub for just this reason. If not, then you will need to get some kind of PWM fan hub, if those are PWM fans. Since you don't list the model of the fans, I'm assuming they are PWM but there are still a lot of 3 pin voltage controlled models out there.
If you need a fan hub, you can simply get something like this (There are MANY different PWM and 3 pin fan hubs to choose from. This one happens to be reasonably priced):
https://www.amazon.com/DEEPCOOL-FH-...s=PWM+fan+hub&qid=1552282020&s=gateway&sr=8-3
Of course, that's only for fan operation and won't be particularly helpful with RGB controls, but if your motherboard has built in RGB controls, depending on the model of the fan, you might not need a separate RGB controller. Hard to say without knowing all the involved hardware.