1)
What is "l'Ratzon"?
1.
Rashi: It should appease You.
2)
What is "Hegyon Libi"?
1.
Radak: It is what I did not say with my mouth, but I thought it in my heart. Also this should be acceptable to You! A person thinks many things, but does not prepare to say them with his lips. This is why David said "Hashem Sefasai Tiftach" (51:17), and Shlomo said "ume'Hashem Ma'ane Lashon" (Mishlei 16:1).
2.
Malbim: I should not have a spoken word or thought that is against Your desire.
3)
Why does he call Hashem "Go'ali"?
1.
Radak: He saves me from Shogeg and Mezid sins.