Add another disk to my existing raid-5 array PERC 6/i without data loss.

Greetings,

This is my current setup. I have one PowerEdge R410 with 4X300GB SAS drive and Perc 6/i raid controller. Currently, I have one RAID-5 virtual disk using 3 disks and the other disk is configured as a spare drive. I want to add the spare drive to my existing RAID-5 array without losing any data! 

On my raid-5 virtual disk, I have a running ESXi system with multiple server. I want to be SURE that I won't lose any data if I reconfigure my Virtual Disk to add my spare drive to my Virtual Disk (raid-5)

I have installed the OM-SrvAdmin-Dell-Web-6.5.0-2247.VIB-ESX41i_A01 on my ESXi server. I have a working Dell OpenManage Server Administrator web page configured on my workstation.