Use OR conditions between other conditions to check if any of them are true rather than all of them, eg:
+ Left arrow key pressed
OR
+ Right arrow key pressed
-> Do stuff...
'Else' can be put in the next event to run when the previous event wasn't true, eg:
+ Left arrow key is down
-> Do stuff...
+ Else
-> Do stuff...
There might be bugs though, so let me know if its not working when you do that...