string.split

function split(str, pat)
   local t = {}
   local fpat = "(.-)" .. pat
   local last_end = 1
   local s, e, cap = str:find(fpat, 1)
   while s do
      if s ~= 1 or cap ~= "" then
     table.insert(t,cap)
      end
      last_end = e+1
      s, e, cap = str:find(fpat, last_end)
   end
   if last_end <= #str then
      cap = str:sub(last_end)
      table.insert(t, cap)
   end
   return t
end

local words = "Soy patito feo"
local printWords = split(words, "%s")
print(printWords[1])
print(printWords[2])
print(printWords[3])
print(table.concat(printWords, " "))