Displaying first cell of a row containing keywords in same column

[xvpnkr]

Hi,

I've had a bit of a hard time with the title, but I think I can explain better what I'm looking for through the problem itself.
I have a sheet with several rows. Each row corresponds to an entry, and columns to dates.
I would like to have a formula that I can expand over a row, which would give me the first cell of the row that contains referenced keywords (preferably quoted in the formula, but that's not really a priority, these can be inputs from another cell as well).
I somewhat managed to get a solution through variations of vlookup and index functions, but what I am completely stuck on 2 aspects:

• Have the matching be partial and for multiple words. So far I only managed to get matches for the first characters, for example it would find "post thread" based on the term "post", but not "thread".
• Have all of the matches listed instead of just the first one in the same cell, not as an array.

Do you have any tips on how to approach this?

Thanks!

 

[xvpnkr]

Made a small example with the top 2 rows manually filled in with the results I would expect.

Book1
	A	B	C
3	red	A	A, B
4	green	B	A
5	A	blue, red	green, red
6	B	green	white, red
7	C	white	blue
8	D	white, blue	blue
Sheet5