As swampyankee points out two solutions are to use \Q or quotemeta. If you want to quote only a subset of metacharacters then the fact that most metacharacters loss their status inside classes can help:

$ perl -wde 0
main::(-e:1):   0
  DB<1> $_ = 'a+b*^c$]d'
  DB<2> s/([+*^\$\]])/\\$1/g
  DB<3> p $_
a\+b\*\^c\$\]d
[download]