Today, Malinga bowled an over with 4 leg-byes, but it was given a maiden over. Then I searched about that and got the details as,

If a bowler delivers a complete over without a run being scored from the bat (even though the opponents may have scored extras by means of byes or leg byes), he has achieved a maiden over. - Source.

I have a doubt, if the bowler bowls a wide or no-ball, will it be considered as a maiden?

The above statement only states about byes or leg-byes, wides and no-balls are also considered as extras. The wide can't be dealt with bat, but a no-ball can get contact with the bat.

So, the clear question is,

What are all the requirements for a maiden over?