($reg_exp = $user_query) =~ s/(\W)/$1 eq '*' ? "\\S*" : "\\$1"/ge;

##</code><code>##

# File as an array of lines:
@matching_lines = grep { /$reg_exp/ } @lines_to_search;

##</code><code>##

# File in a scalar:
@matching_lines = $file =~ /^(.*${reg_exp}.*)$/mg;