Or even single down on the quotes:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $like = q{REGEXP_LIKE(note_tx, 'CA\s+\n?Merged\s+\n?From:\s+\n?Ven
+dor:')};
 print qq{:$like:};
"
:REGEXP_LIKE(note_tx, 'CA\s+\n?Merged\s+\n?From:\s+\n?Vendor:'):
[download]

BTW:  \s includes  \n so  \s+\n? is redundant; might as well just be  \s+