init.vim

function! s:currentFilesList(ArgLead, CmdLine, CursorPos) abort
  let l:head = expand('%:h')
  let l:files = globpath(l:head, a:ArgLead.'*', 0, 1)
  let l:head .='/'
  for i in range(len(l:files))
    if isdirectory(l:files[l:i])
      let l:files[l:i] .= '/'
    endif
    let l:files[l:i] = substitute(l:files[l:i], l:head, '', '')
  endfor
  return l:files
endfunction
command! -bang -complete=customlist,s:currentFilesList -nargs=1 Ce execute 'edit<bang> '.fnameescape(expand('%:h')).'/'.<q-args>