What is the meaning of "Ta'avas Anavim Shamata"?
Radak #1: You heard their prayer, like they desired.
Radak #2: You heard their desire before it left their mouths, like it says "v'Hayah Terem Yikra'u va'Ani E'eneh..." (Yeshayah 65:4).
Malbim: This completes his request [that Hashem will hear their prayer].
What is the meaning of "Tachin Libam"?
Radak: Remove from their hearts worldly distractions, for their hearts are distracted with their poverty and depression. Help them to intend in their hearts for You!
Malbim: Fulfill their desire once it comes on their hearts, even though it did not leave their mouths.
Lev Eliyahu (Shemos p.154): After You will help them prepare their hearts - to eradicate from them pleasures of this world - Your ears will hear (their Tefilah)!
Why does it say "Takshiv Aznecha"?
Radak: [After You help them to intend in their hearts], Your ears will hearken to their prayer.