your code is a little hard to understand!!!
please let me know if this solves your problem

#! /usr/bin/perl -w
use strict;
my @arr=('perl','monks','website');
our @files=('file1.txt','file2.txt','file3.txt');
open(LOG,">","output.txt");
my $file;
foreach $file(@files)
{
 open(FILE,"<",$file);
 my @lines=<FILE>;
 close(FILE);
 my $count=0;
 my $line;
 foreach $line(@lines)
 {
  $count++;
  if($line =~ /.*$arr[0]/)
  {
   print LOG "$arr[0] found in $file at line number $count\n";
  }
  if($line =~ /.*$arr[1]/)
  {
   print LOG "$arr[1] found in $file at line number $count\n";
  }
  if($line =~ /.*$arr[2]/)
  {
   print LOG "$arr[2] found in $file at line number $count\n";
  }
 }
}
close(LOG);
[download]

file1.txt

ansh
batra
perl
postgres
apache
monks
[download]

file2.txt

ansh batra is in perl monks
apache 
postgres
[download]

file3.txt

website
monks perl website
ansh
ansh
website
[download]

output.txt

perl found in file1.txt at line number 3
monks found in file1.txt at line number 6
perl found in file2.txt at line number 1
monks found in file2.txt at line number 1
website found in file3.txt at line number 1
perl found in file3.txt at line number 2
monks found in file3.txt at line number 2
website found in file3.txt at line number 2
website found in file3.txt at line number 5
[download]

thanks!!!
ansh batra