A Jew feels that he cannot find completion without the coming of Moshiach. He therefore constantly hopes for his coming, for without it he feels lacking.
It is because of this that when a Jew mentions Moshiach—even in passing—it awakens in him a longing for the redemption.
This becomes his “basic needs” which an individual is required to pray for and request from the Almighty to complete that which he is lacking, with the coming of Moshiach.
Likutei Sichos 28, pg. 136
 See Rambam, Laws of Prayer, 1:2