If with set operators

Hi guys, I'm trying to run more than one "if" condition at once. What I want is something like

if [[ $a = 1 ]] or [[ $b = 2 ]] or [[ $c = 3 ]]; then
...

I can't remember the syntax for using this or/and set operators. Can someone please assist/ jog my memory?

thanks
Khoom

Sorted -
if [[ $a = 1 ]] || [[ $b = 2 ]] || [[ $c = 3 ]]; then
...

if [[ $a = 1 ]] or [[ $b = 2 ]] or [[ $c = 3 ]]; then

if [ $a -eq 1 -o $b -eq 2 -o $c -eq 3 ]
then
----
else
----
fi