This looks like a job for Text::xSV. Consider:

use strict;
use warnings;
use Text::xSV;

my $line = 'command1 command2 command3 "command4 --some-arg arg --some
+-other-arg 2" command5';

open my $fh, '<', \$line;

my $parser = Text::xSV->new (fh => $fh, sep => ' ');
my @params = $parser->get_row ();

print join "\n", @params;
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Prints:

command1
command2
command3
command4 --some-arg arg --some-other-arg 2
command5
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