This is a song by Barbara Bridge based on parts of Psalm 51. She has an ostinato refrain for the assembly and verses for the cantor that are all over the place, so they’ll need to be on the ball. You’ll need to listen to the YouTube clip to get the idea.
The text is at OCP , who would be happy to sell you the sheet music.
I don’t think my backing is useful here – there is bit too much going on. Just listen to the clip.