excel formula to search Multiple strings in several columns and return strings in a separa

I want a Excel Formula for Search multiple String from Multiple Columns and return Values If Found in different columns. For Example I have Data Like:

In Column A : 3 data: A2: URR/THU/MON ,A3: URR/ETC.C ,A4: URL/ETC.V...........

In Column B : 1 data: B2: URL/THR/RTH ......

Lets assume This Much Data I Have. and I wanted to search URL and URR from column A and B. and Need to return Values in Column C. If 2 value found need to return both with sepearte Coma. I cant Use Nested IF because in that only 7 "IF" I can Use. I have totally more than 25 Keywords to search in more than 20 columns.