RLS DAX Syntax for OR/AND

Hello,

I am messing around with the RLS on PowerBi.com, I can get simple DAX to work i.e. [CHANNEL] = "PNP"

But I would like to create the ability for a user to see 2 CHANNEL. i.e. [CHANNEL] = "PNP" or [CHANNEL] = "OMO"

the other one that I am trying to do is [CHANNEL] = ("PNP or [CHANNEL] = "OMO") and ([REGION] = "R1" or [REGION] = "R2")

But I cant find the correct syntax to do this, has anyone been able to do something similar?