Meanwhile, Ronan O'Gara will take the captain's armband and will partner Munster teammate Pete Stringer at half-back.
Marcus Horan starts alongside Sean Cronin and Tony Buckley in the front row with Rob Kearney, Shane Horgan and Andrew Trimble selected in the back three.
Gavin Duffy comes into the squad and is selected at outside centre to partner the uncapped McFadden in midfield.
Only two of the Leinster side that lost their Magners League final to Ospreys start with full-back Kearney and winger Horgan in action, while Ireland captain Brian O'Driscoll is rested.
Ireland face a Barbarians side that shows 11 changes from their defeat to England, with Xavier Rush captaining the side.
No caps will be awarded for the clash in Limerick after which the Irish squad departs for a three-match tour to New Zealand and Australia.
Ireland: Kearney (Leinster), Horgan (Leinster), Duffy (Connacht), McFadden (Leinster), Trimble (Ulster), O'Gara (Munster), Stringer (Munster), Horan (Munster), Cronin (Connacht), Buckley (Munster), O'Donoghue (Ulster), Tuohy (Ulster), Muldoon (Connacht), Ronan (Munster), Henry (Ulster)
Replacements: Flannery (Munster), Court (Ulster), O'Driscoll (Munster), Wallace (Munster), O'Leary (Munster), Sexton (Leinster), Wallace (Ulster)
Barbarians: Warwick, Smith, Lualala, Rabeni, Heymans, James, Mignoni, Barnes, Brits, Johnston, Thion, O'Kelly, Quinlan, Smith, Rush
Replacements: August, White, So'oialo, Williams, Kelleher, Elissalde, Estebanez or Sackey