let g:surround_no_mappings = 1
function! SurroundOp()
    if v:operator ==# 'd'
        return "<plug>Dsurround"
    elseif v:operator ==# 'c'
        return "<plug>Csurround"
    elseif v:operator ==# 'y'
        return "<plug>Ysurround"
    endif
    return ''
endfunction
omap <expr> s '<esc>'.SurroundOp()