Well, you could do something like this:

use strict;
use warnings;

while (<DATA>) {
    chomp;
    s/^['"]+|['"]+$//g;    # Remove starting and ending quotes
    s/(['"{}])/\\$1/g;     # Escape appropriate characters
    print "$_\n";
}

__DATA__
"text with quotes"
If it ain't broke, don't fix it.
We all love {curly brackets}
[download]

However, you haven't defined what you mean by "metacharacters" or why you're trying to do this exactly, so I can't really supply a comprehensive solution. The "why" is especially important, since what people are asking for often isn't what's actually needed.