Here's an example for those who have more complicated conditions and using Doctrine 2.* with QueryBuilder
:
$qb->where('o.foo = 1')
->andWhere($qb->expr()->orX(
$qb->expr()->eq('o.bar', 1),
$qb->expr()->eq('o.bar', 2)
))
;
Those are expressions mentioned in Czechnology answer.