Check if files exists in PowerShell

I'm trying to copy some files from one diretory to another, check if exists and replace name if yes. And copy all files.

But it gives me the above message:

    cmdlet Copy-Item at command pipeline position 1
    Supply values for the following parameters:
    Path[0]: 
    PS C:\Scripts\MetadataExport> 

What i'm doing wrong?

My code:

  Get-ChildItem -Path "C:\Scripts\MetadataExport\*\*" -Directory | ForEach-Object {  
  $_.FullName | ForEach-Object {Get-ChildItem $_ *.opex | ForEach-Object{If([System.IO.File]::Exists("C:\Scripts\MetadataExport\$Bundles")){While($true){$i=0
  $i++
  $_.Name= $_+$i}
  }Else{Copy-Item -Destination "C:\Scripts\MetadataExport\$Bundles" }}

  Get-ChildItem $_ -Recurse -Include *.xip | ForEach-Object{If([System.IO.File]::Exists("C:\Scripts\MetadataExport\$Bundles")){While($true){$i=0
  $i++
  $_.Name= $_+$i}
  }Else{Copy-Item -Destination "C:\Scripts\MetadataExport\$Resources"}}
  }
  } 

Thanks for any help on this