In Luke 11:9, Jesus was teaching his disciples principles of prayer (see vs. 1). As such, the passage is laying out principles for believers in their prayer life and walk with God through the person of Christ. Verses 9 and following are not a blank check for getting what we want or for treating God like a ‘genie.’ James warns, “You ask and receive not because you ask with wrong motives, so you can spend it on your pleasures” (Jam. 4:3).
Having said that, as God’s children, we do have legitimate needs and, in keeping with the whole of Scripture and what it teaches about prayer and the hindrances to prayer, etc., if we will ask according to God’s will, then we can know that as our Heavenly Father who knows and cares for our needs (our real need and not greed), He will answer according to His timing, purposes, and wisdom.
For more details on prayer and a verse-by-verse study of this passage, see lessons 7 and 8 in Part 2 of the ABCs for Christian Growth series and also the commentary, Luke: The Gospel of the Gentiles on our web site.