This regex could be tweaked a bit so that it doesn't "throw" undefined values into @tokens. But this appears to do what you want in a very straightforward way.

#!/usr/bin/perl -w
use strict;

while (<DATA>)
{
   print "input: $_";
   my @tokens = grep{defined($_)}m/"(.*?)"|(\S+)/g;
   foreach my $tok (@tokens)
   {
       print "   $tok\n";
   }
}

#or
while (<DATA>)
{
   print "input: $_";
   my @tokens = m/"(.*?)"|(\S+)/g;
   foreach my $tok (@tokens)
   {
       next unless defined($tok);
       print "   $tok\n";
   }
}

=prints
input: - "adf adf" - "something else"
   -
   adf adf
   -
   something else
input: "another line" - - "adf"
   another line
   -
   -
   adf
input: abc = 24 "adf adf"
   abc
   =
   24
   adf adf
input: -56 ouy "97 lkh wer" - 87 -98
   -56
   ouy
   97 lkh wer
   -
   87
   -98
=cut

__DATA__
- "adf adf" - "something else"
"another line" - - "adf"
abc = 24 "adf adf"
-56 ouy "97 lkh wer" - 87 -98
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