You can do this with library Isearch+. As far as I know, this is the only library that offers this possibility.
Set or bind option
isearchp-restrict-to-region-flag to non-
nil. This means that when the region is active and you start isearching the search will be limited to the region.
Select the text between the upper-left and lower-right corners of the column you want to search as the active region.
You might want to use
C-x C-x (to
exchange-point-and-mark), depending on which end the cursor is at and which direction you want to search.
Make the region rectangular using
C-x SPC (command
Start isearching (regexp or literal-string search).
isearchp-deactivate-region-flag is non-
nil then the region is automatically deactivated when you start searching, so you can better see the search space.
(You can use
C-x n (command
C-SPC C-SPC (command
isearchp-toggle-region-deactivation) during search to toggle
isearchp-deactivate-region-flag, respectively, but in each case the new value takes effect only when the current search is exited.)
If you use also library Mode-Line Position then not only can you restrict Isearch to the active region but you can keep that restriction when you invoke a query-replacement command from Isearch (e.g.
M-% from Isearch, to use
The main job of that library is to show information about the active region in the mode line. And whenever you invoke a replacement command or Isearch for the active region, that region information is highlighted specially.