I was hoping someone else had answered this because I was trying to do something similar with a custom prompt for task name that contained OR.
Anyway, this is what I came up with for the Custom Prompt condition field that uses an OR statement. Maybe it will help.
name=yellow&name_Mod=cicontains&OR:1:name=blue&OR:1:name_Mod=cicontains&OR:2:name=green&OR:2:name_Mod=cicontains