http://www.fractal-design.com/home/product/cases/define-series/define-r5-black
Water cooling compatibility
Front – 360, 280, 240, 140 and 120 mm radiators of all thicknesses (requires removal of drive bays)
Top – 420, 360, 280, 240, 140 and 120 mm radiators. (A thickness limitation of 55mm for both radiator + fan applies on 420, 280 and 140 mm radiators) (420 and 360 mm radiators require removal of the ODD bay)
Bottom – 120 or 240 mm radiator (Use of radiators in the bottom position limits the PSU length to 165 mm)
Rear – 120 or 140 mm radiator
Corsair says
http://www.corsair.com/en-us/hydro-series-h115i-280mm-extreme-performance-liquid-cpu-cooler
Radiator dimensions: 140mm x 312mm x 26mm
You don't say what dimension gave you trouble.... but best you can do is measure what fits and then find something with smaller dimensions ... I can't give you any specific reference on Corsair CLCs as we will not install CLCs. The only AIOs we will install are the Swiftechs and the EK Predator series
I know ya seem to have heart set on a Corsair but can't recommend any type of water cooling w/ aluminum rads. If ya willing to consider anything else...
The h240-X is shorter, thinner, better thermally and quieter and same price.
http://www.swiftech.com/h240x2.aspx
140 mm x 293 mm x 28 mm
https://www.youtube.com/watch?v=1kf43hPiR6E