I had previous written very breifly about creating a report on disk space using WMI

A much better, and very concise instruction for querying disk information (including %free) can  be found here:

https://msdn.microsoft.com/en-us/library/aa394173(v=vs.85).aspx
This could be easily adapted to be driven from a list of servers in a text file, in a query, or received from something like a net view command

Write-Host "Drive information for MY_Server"

Get-WmiObject -Class Win32_LogicalDisk -ComputerName MY_Server |
    Where-Object {$_.DriveType -ne 5} |
    Sort-Object -Property Name | 
    Select-Object Name, VolumeName, FileSystem, Description, VolumeDirty, `
        @{"Label"="DiskSize(GB)";"Expression"={"{0:N}" -f ($_.Size/1GB) -as [float]}}, `
        @{"Label"="FreeSpace(GB)";"Expression"={"{0:N}" -f ($_.FreeSpace/1GB) -as [float]}}, `
        @{"Label"="%Free";"Expression"={"{0:N}" -f ($_.FreeSpace/$_.Size*100) -as [float]}} |
    Format-Table -AutoSize

OUTPUT:
Drive information for MY_Server

Name VolumeName FileSystem Description             VolumeDirty DiskSize(GB) FreeSpace(GB) %Free
---- ---------- ---------- -----------             ----------- ------------ ------------- -----
A:                         3 1/2 Inch Floppy Drive                        0             0      
C:              NTFS       Local Fixed Disk        False               59.9          5.83 9.74 
D:   Programs   NTFS       Local Fixed Disk        False                200         18.03 9.02 
E:   Product_1  NTFS       Local Fixed Disk        False                250         99.57 39.83
F:   Product_2  NTFS       Local Fixed Disk        False                 20          7.02 35.09
R:   Product_3  MVFS       Network Connection                         78.13         48.83 62.5