use lib is what you need. It is used to add directories to the @INC array, which is a list of the directories to look for files that are require'd or use'd. So above your use myfile statement, add a use lib directory staetment to include the directory that myfile is in.

#!/usr/bin/perl

use strict;
use warnings;

use lib '/home/someuser/somedir';
use myfile;
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Just put in the absolute directory path where i have the directory specified. I know that there is something odd about using '..' in an @INC path, but i cant remember exactly what, someone else should know.