If by our persistence we can get someone to give us something (Lk 11:8), "how much more will the heavenly Father give the Holy Spirit to those who ask Him" (Lk 11:13). Because of God the Father's perfect, infinite love for us, we can be sure that we will receive what we ask for in prayer — or better than what we ask (Eph 3:20; see Catechism, 2737).
However, the writer of the book of James teaches: "You ask and you do not receive because you ask wrongly, with a view to squandering what you receive on your pleasures" (Jas 4:3). The Lord always answers true prayer, that is, prayer coming from love of Him and not from selfishness. However, because of our fallen nature, we are selfish. Does that mean that our prayer is necessarily sabotaged?
The Spirit "helps us in our weakness, for we do not know how to pray as we ought" (Rm 8:26). When we let the Spirit guide us in prayer (see Jn 16:13), we pray not to inform God of our needs or persuade Him to help us. God knows everything. Moreover, He is Love (1 Jn 4:8, 16); so He does not need to be persuaded to love us. But we need information, persuasion, revelation, and transformation. Prayer in the Holy Spirit does not try to help God respond or try to change Him. Prayer in the Spirit praises God for Who He is, while it changes us. Praying in the Holy Spirit, we crucify our flesh and selfishness (Gal 5:24), and therefore prayer in the Spirit is always answered.