There are several ways to design filters in MATLAB. What you want to do would seem to be most suitable for one of the FIR design functions, such as the Signal Processing Toolbox function firls. They allow you to define the pass-bands and stop-bands as well as the amount of attenuation you want.
Signal processing requires experimentation, so this is necessarily going to be an iterative process until you get the result you want.
My usual filter design procedure for IIR filters is here: How to design a lowpass filter for ocean wave data in Matlab? It’s not as directly applicable to your problem as firls, but contains some ideas that you will probably find helpful, especially if you are relatively new to filter design.
