Use an OR with 4 inputs. It's called the Compound Arithmetic function and it's on the Boolean and Numeric palette. Right click on it to Change Mode (Add, Mulitply, AND, OR, XOR).
Another nice thing about the compound arthimetic function is that if you have more complicated boolean operations such as Not A OR B OR Not C, then you can right click on any of the inputs and outpus and select Invert to put a Not operation on them.