file1.txt

needle:filed12:field13:field14:field15:field16
haystack:filed22:field23:field24:field25:field26
lost:filed32:field33:field34:field35:field36

file2.txt

Line,one,fff,ggg,hhh
line,two,hidden,haystack,in,open
Line,three,just,some,junk
line,four,has,needle,here
more,ending,junk.